Method and system for monitoring nutritional uptake as a function of hydrogen gas levels

ABSTRACT

Systems and methods for monitoring nutritional uptake of an individual are disclosed. The method can include monitoring microflora intestinal gas concentration levels associated with a patient and adjusting the volume of nutrient provided by the patient with an artificial feeding device based at least in part on the microflora intestinal gas levels associated with the patient. A microflora intestinal gas sensor can be used to monitor the microflora intestinal gas associated with the patient. The microflora intestinal gas sensor can monitor the microflora intestinal gas in a patient&#39;s exhaled breath or in the patient&#39;s digestive tract. The microflora intestinal gas sensor be included as part of an enteral feeding system at the distal end or outside end of an enteral feeding tube. Systems and methods for monitoring nutritional uptake of an infant based on microflora intestinal gas levels associated with the infant are also disclosed.

This application is a divisional of application Ser. No. 13/245,412, nowU.S. Pat. No. 9,114,065 granted Aug. 25, 2015, entitled “METHOD ANDSYSTEM FOR MONITORING NUTRITIONAL UPTAKE AS A FUNCTION OF MICROFLORAINTESTINAL GAS LEVELS” and filed in the U.S. Patent and Trademark Officeon Sep. 26, 2011, and Applicants hereby claim priority from U.S.Provisional Application No. 61/422,730 filed on Dec. 14, 2010. Theentirety of the prior applications is hereby incorporated by referencein this application.

FIELD OF THE INVENTION

The present disclosure generally relates to a method and system formonitoring the absorption and digestion of nutrients, and moreparticularly to a method and system for continuous, real-time monitoringand regulation of feeding of an individual as a function of microfloraintestinal gas levels generated in the individual's digestive tract.

BACKGROUND OF THE INVENTION

It is important for many patients, particularly critically ill patients,to receive proper nutrition and to begin feeding as soon as possible.Proper nutrition can lead to shorter recovery times and better mortalityand morbidity outcomes. Medical devices that are designed to supportartificial feeding in patients include various enteral feeding systems.Enteral feeding systems typically supply nutrition to a patient'sdigestive tract, specifically the stomach, small intestine or jejunum byinserting a tube down a patient's nose or through the stomach wall.Conversely, parental nutrition is supplied intravenously, circumventingthe usual digestion process. Enteral nutrition is typically recommendedover parenteral nutrition because, if possible, it is important to usethe method closest to natural feeding to keep the gut from shuttingdown.

Once artificial feeding has begun, it is important to assess how wellthe patient is tolerating the artificial feeding, as well as todetermine if the patient is getting adequate nutrition. Manyartificially fed patients can become malnourished due to improperamounts of nutrient being provided to the patient. This problem isenhanced in situations where the care giver slows down the feeding rateto prevent vomiting and diarrhea.

Current clinical methods used to monitor the nutritional uptake andstatus of artificially fed patients include daily blood tests todetermine, for instance, albumin, prealbumin, electrolyte, creatine, andblood sugar levels, and 72 hour fecal fat content tests. In addition,bowel movements, urine assessment, and, if the patient is awake,strength and alertness can be observed. These methods involve long timegaps and do not offer real-time information concerning the patient'snutritional uptake to the care giver.

Thus, there is a need for a real-time nutritional uptake monitoringsystem and method to provide information that a patient is receivingsufficient nutrition. A system and method for informing a care giverwhether too little, an ideal amount, or too much is being fed to thepatient would be particularly useful.

Monitoring nutritional uptake can also be important in the specificfeeding of infants. Parents and other care takers can have a moredifficult time determining when an infant child is hungry or is need offeeding. In addition, weight gain and overall health status is theprimary method of assessing proper nutrient delivery for breast feedinfants. Thus, there is similarly a need for a specific system andmethod of real-time nutritional uptake monitoring to provide informationthat an infant is receiving sufficient nutrition.

SUMMARY OF THE INVENTION

The present invention relates to a method of monitoring artificialfeeding of a patient, comprising: delivering a volume of nutrient to thepatient with a feeding device at an initial feeding rate; monitoring anamount of microflora intestinal gas associated with the patient with agas sensor able to detect microflora intestinal gas; and adjusting thevolume of nutrient delivered to the patient based at least in part onthe amount of microflora intestinal gas associated with the patient.

Additionally, the present invention relates to a system for monitoringartificial feeding of a patient, the system comprising: a feeding deviceconfigured to deliver a volume of nutrient to a patient at an initialfeeding rate; a gas sensor able to detect microflora intestinal gasconfigured to monitor an amount of microflora intestinal gas associatedwith the patient; and a controller configured to adjust the volume ofnutrient delivered to the patient based at least in part on the amountof microflora intestinal gas associated with the patient.

The present invention also relates to a system for monitoringnutritional uptake of an infant, the system comprising: a gas sensorable to detect microflora intestinal gas sensor configured to monitor anamount of microflora intestinal gas associated with the exhaled breathof the infant; an electronic circuit coupled to said gas sensor, theelectronic circuit configured to provide an alert to a care giver basedat least in part on the amount of microflora intestinal gas detected bysaid gas sensor.

Finally, the present invention also relates to a method of monitoringnutritional uptake of an infant, the method comprising: monitoring anamount of microflora intestinal gas level in the exhaled breath of theinfant using a gas sensor able to detect microflora intestinal gas;comparing the amount of microflora intestinal gas with a thresholdvalue; providing an alert if the amount of microflora intestinal gas isless than the threshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, including referenceto the accompanying figures, in which:

FIG. 1 provides a graphical representation of hydrogen concentrationversus feeding over time;

FIG. 2 provides a flow chart of an exemplary method according to anexemplary embodiment of the present disclosure;

FIG. 3 provides a flow chart of an exemplary method for intermittentfeeding according to an exemplary embodiment of the present disclosure;

FIG. 4 provides a graphical representation of hydrogen concentrationversus feeding over time;

FIG. 5 provides a flow chart of an exemplary method for continuousfeeding according to an exemplary embodiment of the present disclosure;

FIG. 6 provides a block diagram of an exemplary system for monitoringnutritional uptake of an artificially fed patient according to anexemplary embodiment of the present disclosure;

FIG. 7 depicts an exemplary system for monitoring nutritional uptake ofan artificially fed patient according to an exemplary embodiment of thepresent disclosure;

FIG. 8 depicts an exemplary system for monitoring nutritional uptake ofan artificially fed patient according to an exemplary embodiment of thepresent disclosure; and

FIG. 9 depicts a block diagram of an exemplary system for monitoringnutritional uptake of an infant according to an exemplary embodiment ofthe present disclosure.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention. It is also understood that whilehydrogen gas is exemplified by way of the figures, the present inventionis not limited to only the concentrations of hydrogen gas but canaccount for all concentrations of microflora intestinal gas levels.

DETAILED DESCRIPTION OF THE INVENTION

While the specification concludes with the claims particularly pointingout and distinctly claiming the invention, it is believed that thepresent invention will be better understood from the followingdescription.

All percentages, parts and ratios are based upon the total weight of thecompositions of the present invention, unless otherwise specified. Allsuch weights as they pertain to listed ingredients are based on theactive level and, therefore; do not include solvents or by-products thatmay be included in commercially available materials, unless otherwisespecified. The term “weight percent” may be denoted as “wt. %” herein.Except where specific examples of actual measured values are presented,numerical values referred to herein should be considered to be qualifiedby the word “about”.

As used herein, “comprising” means that other steps and otheringredients which do not affect the end result can be added. This termencompasses the terms “consisting of” and “consisting essentially of”.The compositions and methods/processes of the present invention cancomprise, consist of, and consist essentially of the essential elementsand limitations of the invention described herein, as well as any of theadditional or optional ingredients, components, steps, or limitationsdescribed herein.

As used herein, the term “microflora intestinal gas” refers to gasessuch as carbon dioxide, oxygen, nitrogen, hydrogen, ammonia, acetone andmethane produced by the microflora present in the intestine as themicroflora break down carbohydrates for absorption through the intestinewall. Since a patient may produce any of these gases, the method of thepresent invention directs the monitoring for artificial feeding towardsthe concentrations of gases delivered by the intestinal walls.

One exemplary embodiment of the present disclosure is directed to amethod of monitoring artificial feeding of a patient. The methodincludes delivering a volume of nutrient to the patient with a feedingdevice, such as an enteral feeding device, at an initial feeding rate.The method further includes monitoring an amount of microfloraintestinal gas associated with the patient with a gas sensor able todetect such microflora intestinal gases; and adjusting the volume ofnutrient delivered to the patient based at least in part on the amountof microflora intestinal gas associated with the patient. For instance,in a particular embodiment, adjusting the volume of nutrient deliveredto the patient comprises adjusting the initial feeding rate of thefeeding device based at least in part on the amount of microfloraintestinal gas associated with the patient.

In a particular aspect of this exemplary embodiment, the feeding devicecan be coupled to a control loop configured to regulate the volume ofnutrient delivered by the feeding device based at least in part on theamount of microflora intestinal gas detected by the gas sensor able todetect microflora intestinal gas.

In another particular aspect of this exemplary embodiment, the methodincludes monitoring an amount of microflora intestinal gas associatedwith the patient before delivering a volume of nutrient to the patientto determine a baseline value of microflora intestinal gas for thepatient. The method can further include determining the relative changein microflora intestinal gas associated with the patient from thebaseline value after delivering a volume of nutrient to the patient andadjusting the volume of nutrient delivered to the patient based at leastin part on the relative change in microflora intestinal gas from thebaseline value.

While the majority of people produce hydrogen gas when digesting food,there are a small percentage of people who do not, i.e. the“non-hydrogen producers”. This is due, in part, to the microbial make upof their gut flora. However, all people produce and exhale methane gas.A system that monitors the concentration levels of methane exhaled, ormore preferably both hydrogen and methane gases exhaled, would allow auniversal monitoring device that could be used for all people. Thebreath analysis unit as shown in FIG. 2 is a good example of anembodiment that measure both hydrogen and methane breath gasessimultaneously. Based on the levels of methane gas present, one coulddetermine if a person was receiving enough nutrition, receiving too muchnutrition or receiving just the right amount of nutrition.

For example, normal methane gas levels before eating(fasting/malnourished) would exhibit a methane range of from about 5 toabout 15 ppm. After eating, a normal methane range would be from about20 to about 60 ppm. If a person is overfed, (danger of vomiting ordiarrhea or pulmonary aspiration) methane levels would be from about 60ppm or above. For people who produce both hydrogen and methane, thenutritional digestion process could also be monitored via the sum ofboth gases which shows a linear dose-effect relationship “Breathhydrogen and methane expiration in men and women after oat extractconsumption,” Behall, K. M., Scholfield, D. J., van der Sluijs, A. M.C., Hallfrisch, J., 128 J. Nutrition 79-84 (1998). In still anotherparticular aspect of this exemplary embodiment, delivering a volume ofnutrient to the patient with the feeding device includes intermittentlydelivering the nutrient to the patient. Adjusting the volume of nutrientdelivered to the patient can include providing nutrient to the patientwith the feeding device when the amount of microflora intestinal gasassociated with the patient is less than a first threshold value. Whendetecting levels of hydrogen gas, for example, nutrients can be providedto a patient intermittently when the levels are less than the thresholdvalue in the range of about 5 ppm to about 25 ppm, such as about 10 ppmto about 20 ppm, such as about 20 ppm, or any other hydrogen gasconcentration therebetween) and stopping delivery of nutrient to thepatient when the amount of hydrogen gas associated with the patient isgreater than a second threshold value (such as greater than a thresholdvalue in the range of about 65 ppm to about 85 ppm, such as about 75 ppmto about 80 ppm, such as about 80 ppm, or any other hydrogen gasconcentration therebetween). When detecting levels of methane gas, forexample, nutrients can be provided to a patient intermittently when thelevels are less than a first threshold value (such as less thanthreshold value in the range of about 3 ppm to about 20 ppm, such asabout 5 ppm to about 15 ppm, such as about 15 ppm, or any other methanegas concentration therebetween) and stopping delivery of nutrient to thepatient when the amount of hydrogen gas associated with the patient isgreater than a second threshold value (such as greater than a thresholdvalue in the range of about 55 ppm to about 65 ppm, such as about 60ppm, or any other hydrogen gas concentration therebetween).

In still a further aspect of this exemplary embodiment, delivering avolume of nutrient to the patient with the feeding device includescontinuously delivering the nutrient to the patient. Adjusting thevolume of nutrient delivered to the patient can include increasing theinitial feeding rate if the detected amount of microflora intestinal gasis less than a first threshold value. When detecting levels of hydrogengas, for example, nutrients can be provided to a patient continuouslywhen the levels are in the range of about 5 ppm to about 25 ppm, such asabout 10 ppm to about 20 ppm, such as about 20 ppm, or any otherhydrogen gas concentration therebetween), maintaining the initialfeeding rate substantially constant if the detected amount of hydrogenis greater than the first threshold value and less than a secondthreshold value (such as a threshold value in the range of about 65 ppmto about 85 ppm, such as about 75 ppm to about 80 ppm, such as about 80ppm, or any other hydrogen gas concentration therebetween), anddecreasing the initial feeding rate if the detected amount of hydrogengas is greater than the second threshold value. When detecting levels ofmethane gas, for example, nutrients can be provided to a patientcontinuously when the levels are less than a first threshold value (suchas a threshold value in the range of about 3 ppm to about 20 ppm, suchas about 5 ppm to about 15 ppm, such as about 15 ppm, or any othermethane gas concentration therebetween), maintaining the initial feedingrate substantially constant if the detected amount of hydrogen/methaneis greater than the first threshold value and less than a secondthreshold value (such as a threshold value in the range of about 55 ppmto about 65 ppm, such as about 60 ppm, or any other methane gasconcentration therebetween), and decreasing the initial feeding rate ifthe detected amount of methane gas is greater than the second thresholdvalue.

In further particular aspects of this exemplary embodiment, monitoringan amount of microflora intestinal gas associated with the patient caninclude monitoring a concentration of microflora intestinal gas in thepatient's breath, such as monitoring a concentration of microfloraintestinal gas in the exhaled breath of the patient. Alternatively,monitoring an amount of microflora intestinal gas associated with thepatient can include monitoring a concentration of microflora intestinalgas in the patient's digestive tract, such as in the patient's stomachor small intestine.

Another exemplary embodiment of the present disclosure is directed to asystem for monitoring artificial feeding of a patient. The systemincludes a feeding device, such as an enteral feeding device, configuredto deliver nutrient to a patient at an initial feeding rate; a gassensor able to detect microflora intestinal gas configured to monitor anamount of microflora intestinal gas associated with the patient; and acontroller configured to adjust the volume of nutrient delivered to thepatient based at least in part on the amount of microflora intestinalgas associated with the patient.

In a particular aspect of this exemplary embodiment, the microfloraintestinal gas sensor includes a sensor configured to monitor theexhaled breath of the patient. For instance, the sensor can be astand-alone breathalyzer sensor device or can be included on aventilator tube used by the patient.

In another particular aspect of this exemplary embodiment, the feedingdevice includes an enteral feeding tube having a distal end insertedinto the digestive tract of the patient and an outside end coupled to anutrient source. In one implementation, the microflora intestinal gassensor can be located at the distal end of the feeding tube such thatthe microflora intestinal gas sensor monitors an amount of microfloraintestinal gas in the stomach of the patient or in the small intestineof the patent. In another implementation, the microflora intestinal gassensor can be located at or near the outside end of the enteral feedingtube.

In still another particular aspect of this exemplary embodiment, thesystem can include an alert system configured to alert a care giverbased at least in part on the amount of microflora intestinal gasdetected by the microflora intestinal gas sensor. For instance, thealert system can provide an alert to a care giver if the amount ofmicroflora intestinal gas associated with the patient is less than orgreater than a particular threshold value. The alert can be an audible,visual, vibratory, wireless, or other suitable alert.

A further exemplary embodiment of the present disclosure is directed toa system for specifically monitoring nutritional uptake of an infant.The system can include a microflora intestinal gas sensor configured tomonitor an amount of microflora intestinal gas associated with theexhaled breath of the infant and an electronic circuit coupled to themicroflora intestinal sensor. The electronic circuit can be configuredto provide an alert, such as an audible, visual, vibratory, or wirelessalert, to a care giver based at least in part on the amount ofmicroflora intestinal gas detected by the microflora intestinal gassensor. For instance, the electronic circuit can be configured toprovide an alert when the amount of microflora intestinal gas detectedby the microflora intestinal gas sensor is less than a threshold value.In a particular implementation of this exemplary embodiment, themicroflora intestinal gas sensor can be incorporated into or can belocated on an oral infant device such as a pacifier, bottle or the likedevice used by the infant. Due to ease, the present invention prefersthe use of a pacifier. However, the ease of use for the presentinvention, does not limit the present method to a pacifier when aninfant is involved. Other devices include, but are also not limited to,bottles, thermometers, teething rings, and the like that may be used todetect the amount of microflora intestinal gases of an infant.

Still a further exemplary embodiment of the present disclosure isdirected to a method for monitoring nutritional uptake for an infant.The method includes monitoring an amount of microflora intestinal gaslevel in the exhaled breath of the infant using a microflora intestinalsensor; comparing the amount of microflora intestinal gas with athreshold value; and providing an alert if the amount of microfloraintestinal gas is less than the threshold value.

The present disclosure is generally directed to methods and systems forreal-time monitoring of nutritional uptake as a function of microfloraintestinal gas generated in the digestive tract. While the presentdisclosure generally discusses the monitoring and regulation ofnutritional uptake in artificially fed patients, those of ordinary skillin the art, using the disclosures provided herein, should understandthat the methods and systems of the present disclosure are applicable toany situation where the nutritional uptake of a person needs to bemonitored. For instance, the systems and methods of the presentdisclosure can be used to monitor nutritional uptake of an infant.

A connection exists between microflora intestinal gas concentration inthe small intestine, stomach, and breath and the absorption of nutrientsin the human body. “Who should request a breath hydrogen test” Li, D-Y,Barnes, T., Thompson, R. E., Cuffari, C., Journal of Applied Research,4(2), 266 (2004); “Hydrogen breath testing in adults,” Lindberg, D. A.,Gastroenterology Nursing, 32(1), 19-24 (2009); “Antibiotic efficacy insmall intestinal bacterial overgrowth.” Attar, A., Flourie, B., Rambaud,J-C., Frachisseur, C., Ruszniewski, P., Bouhnik, Y., Gastroenterology,117(4), 794-797 (1999).

Hydrogen gas and methane gas is produced by the microflora present inthe intestine as the microflora break down carbohydrates for absorptionthrough the intestine wall. In addition, it has been shown that anincrease in the concentration of hydrogen gas correlates to an increasein blood glucose when being fed a specific dose of carbohydrate. “Breathhydrogen and methane excretion patterns in normal man and in clinicalpractice,” Tadesse, K., Smith, D., Eastwood, M. A., 65 Quarterly Journalof Experimental Physiology, 85-97 (1980); “Use of breath hydrogen in thestudy of carbohydrate absorption,” Bond, J. H., Levitt, M. D., DigestiveDiseases, 22(4), 379-382 (1997); “Breath hydrogen and methane expirationin men and women after oat extract consumption,” Behall, K. M.,Scholfield, D. J., van der Sluijs, A. M. C., Hallfrisch, J., 128 J.Nutrition 79-84 (1998). Because of the correlation between microfloraintestinal gas concentration and nutritional uptake, target ranges formicroflora intestinal gas in the breath and/or digestive tract can bedeveloped to inform a care giver that a patient is malnourished, beingfed at the correct rate, or being fed too much and is in danger ofvomiting or diarrhea.

A microflora intestinal gas sensor can be used to monitor theconcentration of microflora intestinal gas in a patient's exhaled breathor in the patient's digestive tract. In fact, the present inventionutilizes a microflora intestinal gas sensor for monitoring aconcentration of microflora intestinal gas from areas that may expelmicroflora intestinal gas from the body. Such areas may be selected fromthe patient's breath, the patient's digestive tract, or the combinationsthereof. Signals received from the microflora intestinal gas sensor canbe compared to threshold values to alert a caregiver that the volume ofnutrient being provided to the patient needs to be increased, decreased,or maintained substantially constant. In addition, the signals receivedfrom the microflora intestinal sensor can be used as part of a feedbackcontrol loop to control a feeding system to increase, decrease, ormaintain the feeding rate as appropriate. In this manner, the methodsand systems of the present disclosure can be used to provide real-timemonitoring and regulation of nutritional uptake in, for instance,artificially fed patients, infants, and other suitable individuals.

Microflora Intestinal Gas Sensors

Gas sensors suitable for providing real-time monitoring and regulationof nutritional uptake of the present invention may be any devicesuitable for detecting expelled microflora intestinal gases. Withoutbeing limited by theory, sensors such as the Optical nose (O-nose),developed by Pranalytica, for example is capable of measuring gases suchas NO, NO2, NH3, SO2 and CH4. Accordingly, this optical device could bedesigned for the detection microflora intestinal gas concentrations fromthe expired breath. Additionally, City Technology offers variousindustrial as well as medical grade hydrogen sensors that may also besuitable to carry out the present invention. Further, a sensors systemhas been developed by Costello et al to monitor various VoCs in exhaledbreath as shown in FIG. 6. The sensors are based on electrochemical gassensors such as hydrogen, CO, H2S, ethanol, and ammonia. Finally,Argonne National Lab has developed palladium nanobeads for a fast aswell as sensitive hydrogen detection particularly for fuel cellapplications. This nanosensor shows high selectivity and could detect H2in presence of oxygen, humidity and other gases. These and othersimilarly functioning devices capable of detecting the microfloraintestinal gas concentration levels may be used and/or designed to carryout the methods of the present invention.

Microflora present in the intestine is able to produce gases such ascarbon dioxide, oxygen, nitrogen, hydrogen, ammonia, acetone and methaneas the microflora break down carbohydrates for absorption through theintestine wall. Methods of the present invention are able to detect thelevels of such gases in order to aid in monitoring nutritional uptake.Specifically, methods of the present invention may comprise monitoringthe levels of microflora intestinal gases produced by a patient. Methodsof the present invention may further comprise the monitoring ofmicroflora intestinal concentrations. Illustrations included herein,show, for example, concentrations of hydrogen gas. Again, it isunderstood that while the illustrations of the present specificationshow hydrogen gas concentration, the same figures could be depicted forall microflora intestinal gas concentrations.

Exemplary regulation of nutritional uptake based on hydrogen gasconcentration is illustrated in FIG. 1. FIG. 1 depicts two hydrogenconcentration thresholds X1 and X2. Thresholds X1 and X2 are determinedsuch that hydrogen gas concentrations of less than threshold X1 indicatethat the patient is malnourished and hydrogen gas concentrations ofgreater than threshold X2 indicate that the patient is being overfed.Hydrogen gas concentrations greater than X1 and less than X2 indicatethat the patient is receiving an ideal amount of nutrition.

FIG. 1 illustrates two hypothetical curves 20, 30 of hydrogen gasconcentration over time. Curve 20 is associated with continuousartificial feeding of a patient over time. Curve 30 is associated withintermittent artificial feeding of a patient over time. As illustratedin FIG. 1, with proper monitoring provided by the systems and methods ofthe present disclosure, the hydrogen gas concentration associated withcurves 20 and 30 can be maintained between X1 and X2 such that thepatient is receiving an ideal amount of nutrition. Should the curves 20,30 ever fall below threshold X1 or exceed threshold X2, the systems andmethods of the present disclosure could alert a care giver that thepatient is not receiving the proper amount of nutrition. In addition,the volume of nutrient provided to the patient can be adjusted such thatthe proper amount of nutrient is provided to the patient.

For example, FIG. 2 illustrates an exemplary method 200 for monitoringnutritional uptake based on hydrogen gas concentration according to anexemplary embodiment of the present disclosure. The method 200 can beused to calibrate an artificial feeding system or to determine whetherthe initial feeding rate of nutrient provided by the artificial feedingsystem is sufficient to provide adequate nutrition to the patient.

As shown in FIG. 2 at 210, a baseline value of hydrogen gas associatedwith the patient is determined before any nutrient is delivered to thepatient by the artificial feeding system. The baseline value of hydrogengas can be determined using a hydrogen gas sensor as will be discussedin more detail below.

At 220, a volume of nutrient is delivered to the patient with theartificial feeding system at an initial feeding rate. As used herein,the term feeding rate is intended to refer to the rate nutrient isdelivered to the patient with an artificial feeding system.

At 230, the hydrogen gas concentration associated with the patient isagain monitored with the hydrogen gas sensor. Step 230 can be performedafter sufficient passage of time, such as 15 minutes, to allow foradequate absorption of nutrients into the patient. At 240, the relativechange in hydrogen gas concentration from the baseline value isdetermined, for instance, by subtracting the baseline value of hydrogengas from the monitored hydrogen gas concentration.

At 250, the relative change in hydrogen gas concentration is compared toa threshold value. For instance, in a particular embodiment, therelative change in hydrogen gas can be compared to a first thresholdvalue. The first threshold value can be set such that a relative changein hydrogen gas that falls below the first threshold value indicatesthat the patient is not receiving adequate nutrition. If the relativechange in hydrogen gas concentration exceeds the first threshold value,the artificial feeding system is providing sufficient nutrition to thepatient and no increase to the volume of nutrient being delivered to thepatient is necessary.

As shown at 260, if the relative change in hydrogen gas concentration isless than the first threshold value, the patient is not receiving anadequate amount of nutrients from the feeding system and an alert, suchas an audible, visual, vibratory, or wireless alert, is provided to athe care giver indicating to the care giver that the patient is notreceiving adequate nutrition. At 270, the volume of nutrient deliveredto the patient is increased, for instance, by increasing the initialfeeding rate of the feeding device. The volume of nutrient can bemanually increased by the care giver upon receiving the alert or can beincreased automatically by a control loop that adjusts the feeding rateof the artificial feeding system based on the hydrogen gas levelsassociated with the patient. In this way, the method 200 adjusts thevolume of nutrient delivered to the patient based on the amount ofhydrogen gas associated with the patient and provides for regulation ofthe amount of nutrient delivered to the patient based on hydrogen gasconcentration levels.

In a variation or in addition to the exemplary method illustrated inFIG. 2, the relative change in hydrogen gas can be compared to a secondthreshold value. The second threshold value can be set such that arelative change in hydrogen gas that exceeds the second threshold valueindicates that the patient is receiving too much nutrition. If therelative change in hydrogen gas concentration is greater than the secondthreshold value, the patient is receiving too much nutrient and is indanger of vomiting and/or diarrhea. An alert, such as an audible,visual, vibratory, or wireless alert, can be provided to a the caregiver indicating to the care giver that the patient is receiving toomuch nutrition. The volume of nutrient delivered to the patient can thenbe decreased, for instance, by decreasing the initial feeding rate ofthe feeding device.

FIG. 3 illustrates another exemplary method 300 associated withmonitoring nutritional uptake based on hydrogen gas concentrationassociated with a patient. The method 300 can be used to monitor andregulate the intermittent feeding of the patient with an artificialfeeding system. In particular, the method 300 can be used to determinethe start and stop times for intermittent feeding of the patient withthe artificial feeding system.

At 310, a volume of nutrient is delivered to the patient at an initialfeeding rate. The volume of nutrient can be delivered by an enteralfeeding system. At 320, the hydrogen gas concentration associated withthe patient is monitored using a hydrogen gas sensor. For instance, ahydrogen gas sensor can be used to monitor the amount of hydrogen gas inthe patient's exhaled breath or in the patient's digestive tract.

At 330, the hydrogen gas concentration is compared to a first thresholdvalue, such as first threshold value T1 illustrated in FIG. 4. The firstthreshold value can be, for instance, in the range of about 5 ppm toabout 25 ppm, such as about 10 ppm to about 20 ppm, such as about 20ppm, or any other hydrogen gas concentration therebetween. If thehydrogen gas concentration is less than first threshold value, thepatient is in need of additional nutrition. Accordingly, referring backto FIG. 3, an alert can be provided to the care giver from an alertsystem as shown at 340. In addition, the volume of nutrient delivered tothe patient from the feeding system can be increased as shown 350 toaccommodate the patient's need for additional nutrition. A care givercan manually increase the volume of nutrient delivered to the patient,or a control loop can automatically adjust feeding system parameters toincrease the volume of nutrition delivered to the patient. Afterincreasing the volume of nutrient delivered to the patient, the method300 returns to 320 and continuously monitors the hydrogen gas associatedwith the patient to determine if the patient is receiving too little, anideal amount, or too much nutrition.

At 360, the hydrogen gas concentration is compared to a secondthreshold, such as threshold T2 illustrated in FIG. 4. Second threshold,for instance, can be in the range of about 65 ppm to about 85 ppm, suchas about 75 ppm to about 80 ppm, such as about 80 ppm, or any otherhydrogen gas concentration therebetween. If the hydrogen gasconcentration is less than the second threshold value, but greater thanthe first threshold, the patient is receiving an ideal an amount ofnutrition. Thus, no adjustments to the feeding system are necessary andthe method 300 continues to monitor hydrogen gas concentrationsassociated with the patient.

If the hydrogen gas concentration exceeds the second threshold value,the patient is receiving too much nutrition and is in danger of vomitingor diarrhea. An alert can be provided to the care giver from an alertsystem as shown at 370. To prevent overfeeding, the method 300 will stopdelivering nutrient to the patient and will continue to monitor hydrogengas associated with the patient as shown at 380. When the hydrogen gaslevels fall below the first threshold, the method 300 will begindelivering nutrient to the patient again to prevent the patient frombecoming malnourished.

FIG. 4 provides a graphical illustrated of hydrogen gas concentrationlevels associated with a patient that is being intermittently fedaccording to the method 300 of FIG. 300. As illustrated, the hydrogengas level associated with the patient increases past threshold T1 as theartificial feeding system delivers a volume of nutrient to the patient.As the patient is fed, the hydrogen gas levels may approach thresholdT2. If the hydrogen gas level associated with the patient exceedsthreshold T2, the artificial feeding system stops delivering nutrient tothe patient. This causes the hydrogen gas levels associated with thepatient to decrease until the hydrogen gas levels drop below thresholdT1. The artificial feeding system then again delivers nutrient to thepatient, causing an increase in hydrogen gas concentration associatedwith the patient.

FIG. 5 illustrates another exemplary method 500 associated withmonitoring nutritional uptake based on hydrogen gas concentrationassociated with a patient. The method 500 can be used to monitor andregulate the continuous feeding of the patient with an artificialfeeding system. The method 500 is similar to the method 300 of FIG. 3,except the method 500 adjusts the feeding rates of the artificialfeeding system as opposed to the start and stop times associated withthe delivery of nutrition to the patient. This ensures that nutrient iscontinuously delivered to the patient at an ideal feeding rate toprevent malnourishment and overfeeding.

For instance, at 510 a volume of nutrient is delivered to the patient atan initial feeding rate. The volume of nutrient can be delivered by anenteral feeding system. At 520, the hydrogen gas concentrationassociated with the patient is monitored using a hydrogen gas sensor.For instance, a hydrogen gas sensor can be used to monitor the amount ofhydrogen gas in the patient's exhaled breath or in the patient'sdigestive tract.

At 530, the hydrogen gas concentration is compared to a first thresholdvalue, such as a threshold value in the range of about 5 ppm to about 25ppm, such as about 10 ppm to about 20 ppm, such as about 20 ppm, or anyother hydrogen gas concentration therebetween. If the hydrogen gasconcentration is less than first threshold value, the patient is in needof additional nutrition. Accordingly, an alert can be provided to thecare giver from an alert system as shown at 540. In addition, theinitial feeding rate of the feeding system can be increased toaccommodate the patient's need for additional nutrition as shown at 550.A care giver can manually increase the initial feeding rate, or acontrol loop can automatically adjust feeding system parameters toincrease the initial feeding rate delivered to the patient. Afterincreasing the initial feeding rate delivered to the patient, the method500 returns to 520 and continuously monitors the hydrogen gas associatedwith the patient to determine if the patient is receiving too little, anideal amount, or too much nutrition.

At 560, the hydrogen gas concentration is compared to a secondthreshold, such as a threshold value in the range of about 65 ppm toabout 85 ppm, such as about 75 ppm to about 80 ppm, such as about 80ppm, or any other hydrogen gas concentration therebetween. If thehydrogen gas concentration is less than the second threshold value, butgreater than the first threshold, the patient is receiving an ideal anamount of nutrition. Thus, no adjustments to the feeding system arenecessary and the method 500 continues to monitor hydrogen gasconcentrations associated with the patient.

If the hydrogen gas concentration exceeds the second threshold value,the patient is receiving too much nutrition and is in danger of vomitingor diarrhea. An alert can be provided to the care giver from an alertsystem as shown at 570. At 580 to prevent overfeeding, the method 500will decrease the initial feeding rate and will continue to monitorhydrogen gas associated with the patient. When the hydrogen gas levelfall below the first threshold, the method 500 will increase the initialfeeding rate to prevent the patient from becoming malnourished.

With reference to FIG. 6, an exemplary system 100 for carrying out themethods disclosed above will now be discussed in detail. As illustratedin FIG. 6, the system 100 includes a controller 110, a hydrogen gassensor 120, a feeding system 130, a user interface 140, and an alertsystem 150. Feeding system 130 can be any system used to delivernutrient to a patient, such as an enteral feeding system. For instance,in a particular embodiment, feeding system 130 can include an enteralfeeding tube 135 (illustrated in FIG. 7 and FIG. 8) having a distal endinserted into the digestive tract of a patient and a nutrient source.The enteral feeding tube can be inserted into the patient either throughthe stomach wall of the patient or down the patient's nose or throat.Nutrient is delivered to the patient through enteral feeding tube 135from the nutrient source at an initial feeding rate controlled bycontroller 110.

Controller 110 is configured to control feeding system 130 based onsignals received from hydrogen gas sensor 120 to ensure that feedingsystem 130 delivers a proper amount of nutrition to a patient.Controller 110 can be any suitable control device, and can include, forinstance, a microcontroller or other control circuitry. User interface140 can be coupled to controller 110. User interface 140 can be adaptedto receive instructions through various peripheral devices from a user.For instance, a user can input commands or other data into userinterface 140 through a keyboard, touch-screen, mouse, or other suitableinput device. User interface 140 can display data and other informationassociated with system 100 to a user through a visual display, mediaelement, or other suitable output device.

Controller 110 is coupled to an alert system 150. Controller 110 isconfigured to control alert system 150 to provide an alert to a caregiver based on hydrogen gas levels associated with the patient. Forinstance, if controller 110 determines that the hydrogen gas levelassociated with a patient is less than a threshold value, the controller110 can control alert system 150 to provide an alert to a care giverindicating that the care giver is in need of additional nutrition. Thealert can be a visual alert, audible alert, vibratory alert, wirelessalert, or other suitable alert.

Hydrogen gas sensor 120 is configured to monitor hydrogen gas levelsassociated with the patient. Hydrogen gas sensor 120 can be any devicethat can monitor the hydrogen gas levels generated in a patient'sdigestive tract as a result of nutritional uptake of the patient.

In a particular embodiment, the hydrogen gas sensor 120 is configured tomonitor hydrogen gas in the patient's exhaled breath. The hydrogen gassensor 120 can be a breathalyzer sensor such as the HBT Sleuth sensormanufactured by Bedford Scientific Ltd. Other suitable sensors includegas chromatography mass spectroscopy (GC-MS) and direct massspectroscopy sensors that analyze the chemical composition of acollected gas sample. The hydrogen sensor 120 can be a stand-alonebreathalyzer sensor that a patient breaths into periodically or can beincorporated as part of a ventilator tube for a patient that is using aventilator system.

The very small size of certain hydrogen gas sensors can make themsuitable for incorporation into an enteral feeding system for monitoringhydrogen gas in a patient's digestive tract. In this regard, thehydrogen gas sensor 120 can be included as part of an enteral feedingsystem that delivers nutrition to a patient's digestive tract.

For instance, as illustrated in FIG. 7, the hydrogen gas sensor 120 canbe included on the distal end of enteral feeding tube 135. Asillustrated in FIG. 7, the hydrogen gas sensor 120 is located in thestomach 182 of patient 180. Alternatively, the hydrogen gas sensor 120could be located in the small intestine 184 of patient 180. The hydrogengas sensor 120 monitors hydrogen gas levels contained in stomach 182 orsmall intestine 184 and communicates signals associated with thehydrogen gas levels to controller 110 over communications link 125.Communications link 125 can be a hardwired communication link, such asan optical communication link 125 or other suitable hardwiredcommunication link. Alternatively, hydrogen gas sensor 120 can beconfigured to communicate wirelessly with controller 120.

Various hydrogen sensors are suitable for use as hydrogen gas sensor 120located at the distal end of enteral feeding tube 135. For instance,hydrogen gas sensor 120 can be an Optical nose (O-nose) sensor developedby Pranalytica; one of various medical grade sensors manufactured byCity Technology, including the model 3HYT, 3MHYT, 4HYT, 7HYE, 7HYT,EZT3HYE, or EZT3HYT sensors; or palladium nanobeads manufactured byArgonne National Laboratories.

Other nanosensors, such as, for example, ZnO nanorod hydrogen sensorsdeveloped at University of Florida (Lupan O et al., 2009; “Selectivehydrogen gas nanosensors using individual ZnO nanowire with fastresponse at room temperature,” Sensors and Actuators B Chemical);titanium nanotubes developed at Penn State (Varghese O. K., et al.,2003; “Hydrogen sensing using titania nanotubes,” Sensors and Actuators,B93, pp 338-344); and/or the nanoflowers (Shafiei M et al., 2010,“Pt/MoO3 nano-flower SiC Schottky diode based hydrogen gas sensors,”Prof of IEEE Sensors Conf. 2010, 354-357) could be used as hydrogen gassensor 120. Oriented graphite nanostructure carbon films that have beenemployed as a chemiresistive sensor for ultra-sensitive gas sensorapplications may also be suitable for hydrogen gas sensor 120 (Rivera IF et. al., 2010; “Graphene based ultra-sensitive gas sensors;” Prof ofIEEE Sensors Conf. 2010, 1543-37; Moafi A et al., 2010; “Orientedgraphitic carbon films for hydrogen gas sensors,” Prof of IEEE SensorsConf. 2010, 378-381).

As illustrated in FIG. 8, hydrogen gas sensor 120 can alternatively belocated on the outside end of enteral feeding tube 120, such asproximate a nutrient source for feeding system 130. The hydrogen gassensor 120 monitors hydrogen gas levels contained in the digestive tractof the patient and communicates signals associated with the hydrogen gaslevels to controller 110 over communications link 125.

Referring to FIG. 9, an exemplary system 400 for monitoring nutritionaluptake of an infant is disclosed. The system includes electroniccircuitry, such as controller 410 and alert system 430, and a hydrogengas sensor 420 located as part of a an oral infant device such as apacifier, bottle or the like device. The hydrogen gas sensor 420 isconfigured to monitor an amount of hydrogen gas associated with theexhaled breath of the infant. The controller 410 monitors signalsreceived from the hydrogen gas sensor 420 and controls alert system 430to provide an alert based on the hydrogen gas level detected by thehydrogen gas sensor 420. The alert can be an audible alert, visualalert, vibratory alert, wireless alert, or other suitable alert.

For instance, in a particular embodiment, the hydrogen gas sensor 420can monitor the amount of hydrogen gas in the exhaled breath of theinfant. The controller 410 can receive signals from the hydrogen gassensor 420 and compare the detected the amount of hydrogen gas with athreshold value. The controller 420 can control the alert system toprovide an alert 430 if the amount of hydrogen gas is less than thethreshold value. The alert can indicate to a parent or other care giverthat the infant is need of additional nutrition and that it is time forfeeding.

The exemplary system 400 can be used for instance, by a mother who isbreast feeding an infant. A mother that is breast feeding an infant maybe unsure whether the infant has received adequate nutrition. Todetermine if the infant has received adequate nutrition, the mother canmonitor the exhaled breath of the infant using a hydrogen gas sensor420, such as a hydrogen gas sensor incorporated as part of a an oralinfant device such as a pacifier, bottle or the like device used by theinfant. The hydrogen gas levels can be compared to a threshold value andif the hydrogen gas levels associated with the infant are less than athreshold value, the system 400 can provide an alert through alertsystem 430 to the mother or other care giver indicating that the babyhas not received sufficient nutrition. The mother can then continuebreast feeding the infant until the infant has received adequatenutrition.

Example

1. Sensitivity of Hydrogen Gas Sensor

A hydrogen gas sensor was purchased from Bedfont Scientific Inc.,Rochester, Kent UK). The system was calibrated using background air (0ppm hydrogen) and with a sample cylinder containing 100 ppm hydrogen gas(Microdirect Inc., Auburn Me.). The gas stream was allowed to gentlyblow into the intake of the measure during a reading phase. The sensormeasured 100 ppm hydrogen.

2. Monitoring Breath Hydrogen Gas During the Day/Evening in a HumanSubject

A healthy male subject (53 yr old) measured his breath hydrogen duringthe day and evening hours to determine the changes due to feeding. Thesubject gently inhaled breath, held it for 20 seconds and then gentlyexhaled through his mouth into the sensor. The results are shown below:

-   -   5:30 am—Breath hydrogen measured after fasting since 10 pm the        night before; 15 ppm    -   Breakfast at 6:30 am    -   7 am—Breath hydrogen measured; 48 ppm    -   11:30 am—Breath hydrogen measured; 20 ppm    -   Lunch at 11:40 am    -   12 noon—Breath hydrogen measured; 45 ppm    -   1 pm—Breath hydrogen measured; 55 ppm    -   6 pm—Breath hydrogen measured; 15 ppm    -   Dinner at 7 pm    -   8 pm—Breath hydrogen measured; 64 ppm        The above results show that breath hydrogen does correlate well        to the nutritional uptake of the subject and also to when the        subject is feeling hungry.

3. Experiment to Model Feeding Tube with Sensor at Distal End InsideStomach.

The Perspex model of the stomach and small intestine was used. To thedistal end of an enteral feeding tube was attached the hydrogen gassensor (taped) and this adapted tube was inserted into the stomach via ahole in the stomach wall. A cylinder of 100 ppm hydrogen gas in air wasthen attached to the bottom of the small intestine tube of the model anda steady stream of gas introduced into the model. A hydrogen gasconcentration was then measured by the sensor. The reading was 100 ppm.

4. Experiment Using and Enteral Feeding Tube with Hydrogen Sensor at theOutside of the Tube (Skin Surface at the Stomach)

The hydrogen sensor was mounted on the outside end of the enteralfeeding tube where the tube end is on the outside of the stomach on theskin surface. Hydrogen gas at 100 ppm was introduced into the stomachand small intestine via the small intestine tube. The hydrogen gasconcentration of the gas exiting the tube was measured by the sensor andwas found to be 100 ppm.

These and other modifications and variations to the present inventionmay be practiced by those of ordinary skill in the art, withoutdeparting from the spirit and scope of the present invention, which ismore particularly set forth in the appended claims. In addition, itshould be understood that aspects of the various embodiments may beinterchanged both in whole or in part. Furthermore, those of ordinaryskill in the art will appreciate that the foregoing description is byway of example only, and is not intended to limit the invention sofurther described in such appended claims.

What is claimed:
 1. A system for monitoring artificial feeding of apatient, the system comprising: a feeding device configured to deliver avolume of nutrient to a patient at an initial feeding rate; a microfloraintestinal gas sensor configured to monitor an amount of microfloraintestinal gas associated with the patient; and a controller configuredto adjust the volume of nutrient delivered to the patient based at leastin part on the amount of microflora intestinal gas associated with thepatient; wherein the feeding device is configured to deliver the volumeof nutrient to the patient with both continuous and intermittentdelivery separately, and wherein the feeding device is configured toprovide nutrient to the patient when the amount of microflora intestinalgas associated with the patient is less than a first threshold value andto stop delivery of nutrient to the patient when the amount ofmicroflora intestinal gas associated with the patient is greater than asecond threshold value.
 2. The system of claim 1, wherein said feedingdevice comprises an enteral feeding device having a distal end insertedin said patient and an outside end coupled to a nutrient source.
 3. Thesystem of claim 2, wherein said microflora intestinal gas sensor islocated at the distal end of said enteral feeding tube.
 4. The system ofclaim 2, wherein said microflora intestinal gas sensor is located at theoutside end of said enteral feeding tube.
 5. The system of claim 1,wherein said microflora intestinal gas sensor comprises a sensorconfigured to monitor exhaled breath of the patient.
 6. The system ofclaim 1, wherein said microflora intestinal gas sensor is configured tomonitor the amount of microflora intestinal gas in areas selected fromthe stomach and the small intestine of the patient.
 7. The system ofclaim 1, wherein said system further comprises an alert systemconfigured to provide an alert to a caregiver based at least in part onthe amount of microflora intestinal gas monitored by said microfloraintestinal gas sensor.
 8. The system of claim 1, wherein the system isconfigured to monitor the amount of microflora intestinal gas associatedwith the patient before delivering the volume of nutrient to the patientwith the feeding device to determine a baseline value of microfloraintestinal gas, and wherein the system is configured to determine arelative change in microflora intestinal gas associated with the patientfrom the baseline value after delivering the volume of nutrient to thepatient to adjust the volume of nutrient delivered to the patient basedat least in part on the relative change in microflora intestinal gas. 9.The system of claim 1, wherein the feeding device is coupled to acontrol loop configured to regulate the volume of nutrient delivered bythe feeding device based at least in part on the amount of microfloraintestinal gas monitored by the microflora intestinal gas sensor. 10.The system of claim 1, wherein the feeding device is configured toincrease the initial feeding rate if the monitored amount of microfloraintestinal gas is less than a first threshold value, maintain theinitial feeding rate substantially constant if the monitored amount ofmicroflora intestinal gas is greater than the first threshold value andless than a second threshold value, and decrease the initial feedingrate if the monitored amount of microflora intestinal gas is greaterthan the second threshold value.
 11. The system of claim 10, wherein thefirst threshold value is in the range of about 3 ppm to about 25 ppm andthe second threshold value is in the range of about 65 ppm to about 85ppm.
 12. The system of claim 1, wherein the microflora intestinal gassensor is configured to monitor the amount of microflora intestinal gasfrom areas selected from the patient's breath, the patient's digestivetract, and combinations thereof.
 13. The system of claim 1, wherein themicroflora intestinal gas is hydrogen.
 14. The system of claim 13,wherein monitoring the amount of the microflora intestinal gasassociated with the patient includes monitoring a concentration of themicroflora intestinal gas associated with the patient.
 15. A system formonitoring artificial feeding of a patient, the system comprising: afeeding device configured to deliver a volume of nutrient to a patientat an initial feeding rate; a microflora intestinal gas sensorconfigured to monitor an amount of microflora intestinal gas associatedwith the patient; and a controller configured to adjust the volume ofnutrient delivered to the patient based at least in part on the amountof microflora intestinal gas associated with the patient; wherein thefeeding device is configured to provide nutrient to the patient when theamount of microflora intestinal gas associated with the patient is lessthan a first threshold value and to stop delivery of nutrient to thepatient when the amount of microflora intestinal gas associated with thepatient is greater than a second threshold value.
 16. The system ofclaim 15, wherein monitoring the amount of the microflora intestinal gasassociated with the patient includes monitoring a concentration of themicroflora intestinal gas associated with the patient, and wherein thefirst threshold value is in the range of about 3 ppm to about 25 ppm andthe second threshold value is in the range of about 65 ppm to about 85ppm.
 17. The system of claim 15, wherein the microflora intestinal gasis hydrogen.
 18. A system for monitoring artificial feeding of apatient, the system comprising: a feeding device configured to deliver avolume of nutrient to a patient at an initial feeding rate; a microfloraintestinal gas sensor configured to monitor an amount of microfloraintestinal gas associated with the patient; and a controller configuredto adjust the volume of nutrient delivered to the patient based at leastin part on the amount of microflora intestinal gas associated with thepatient; wherein the feeding device is configured to increase theinitial feeding rate if the monitored amount of microflora intestinalgas is less than a first threshold value, maintain the initial feedingrate substantially constant if the monitored amount of microfloraintestinal gas is greater than the first threshold value and less than asecond threshold value, and decrease the initial feeding rate if themonitored amount of microflora intestinal gas is greater than the secondthreshold value.
 19. The system of claim 18, wherein monitoring theamount of the microflora intestinal gas associated with the patientincludes monitoring a concentration of the microflora intestinal gasassociated with the patient, and wherein the first threshold value is inthe range of about 3 ppm to about 25 ppm and the second threshold valueis in the range of about 65 ppm to about 85 ppm.
 20. The system of claim18, wherein the microflora intestinal gas is hydrogen.